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Design for a wetter future today

28 February, 2013 | By Robert Barker

New approaches to flood prevention can drive innovative design, writes Robert Barker

The Met Office declared 2012 to be the wettest year in England and the second wettest in the whole of the UK in the past 100 years. Similarly, The Guardian reported that ‘days of extreme rainfall - downpours which are expected once every 100 days - occurred every 70 days in 2012.’ With extreme events becoming more commonplace, we must start to design for a wetter future today.

Last year’s publication of the World Bank report Cities and Flooding, A Guide to Integrated Urban Flood Risk Management for the 21st Century: A Summary for Policy Makers, to which Baca Architects contributed, outlines 12 key principles for integrated urban flood risk management. The report stresses the impossibility of entirely eliminating flood risk, but it argues that, through multi-stakeholder cooperation, significant wins can be achieved. The report also highlights the important fact that heavily engineered solutions are not necessarily always best; they may just transfer problems up or downstream.

Flood risk is considered another design obstacle with a high price tag

Flood risk is one of the many constraints that architects need to consider from the beginning of a project. Often this is viewed as just another obstacle with a high price tag. A new approach to living with floods, however, can be the driver of more innovative architecture and landscape design, particularly if we are prepared to live with water, rather than just design it out. Lower land levels need to be designed to cope with regular water inundation, while higher land levels can be designed to withstand occasional flooding. Solutions are not black and white, so therefore require a nuanced, hierarchical approach in which design will respond to differing levels of inundation.

Computer modelling can be used to predetermine where floodwater will flow, such that parts of the landscape can be engineered to absorb floodwater, with other areas designed to store rainwater runoff, preventing it from further overwhelming drains and rivers. If areas of landscape are specifically contoured to encourage flooding, water is diverted away from neighbouring properties. ‘Floodable’ land can also be used as a productive part of the design solution, providing space for play areas, parking, footpaths and space-hungry renewable energy technologies (such as heat exchange, solar panels and wind turbines).

We require a nuanced, hierachical approach in which design will respond to differing levels of water inundation

Varying heights and velocities of floodwater require different solutions, just as we employ a range of technologies to deal with different energy requirements or fire risks. Where flood levels are significant, buildings need to be elevated, wetproof (built so water can pass through the building) or floating. This approach is illustrated by Baca’s ‘amphibious’ house in Marlow, Buckinghamshire, which is scheduled to start on site next month.

Where flood levels are lower, buildings can be elevated or dryproof (where water is prevented from entering the building by barriers and waterproofing). When tackled with creativity, this added complexity can actually deliver better places.

Creating space for water through multifunctional space within redevelopment sites has other benefits, too. It can substantially reduce the urban heat island effect and improve health and wellbeing by creating attractive, green environments for people to live in. Often this is the only solution to redeveloping challenging brownfield sites.

As our climate changes and flood risk becomes more severe, an integrated approach to flood design will become a necessity. Isn’t it better that we start building in this way now?

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The Architects' Journal is the voice of architecture in Britain. We sit at the heart of the debate about British architecture and British cities, and form opinions across the whole construction industry on design-related matters